Okay, the support gave me a good way to complete the quest. I abandoned all my other quests that I had so I only had the God of Schemes quest left. I then logged out and took like a break for 20-30 minutes. Logged back in again, played the quest and everything had been reseted. I was able to complete the quest. Abnur Tharn talked to me once I got inside Heart's Grief and the Titan flew into the room where you either can free Mannimarco or just let him stay there. After that everything was the same as before for me but I could finally get talk to Meridia inside The Colored Rooms and reclaim my soul.

So for those that still are stuck on this quest inside The Colored Rooms or even stuck after Molag Bal have got down on his knees, try this atleast. Worked for me and it will probably work for you too.

i am currently in the same position as Taresha. i did a bug report but i am not sure if there is anything else i should do. i have done the quest through on a few other toons with no issues. personaly i would not mind at all if CS just auto finished the quest for me and let me get back to playing while they figure out how to fix it.

Same issue here, even after relog. This Quest should really be given high priority to fix, regardless of workarounds.